The work done in moving a 1 C charge over an equipotential surface in X-direction through a distance of 20 cm is:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Zero
The work done in moving a charge between two points is \( W = q\,(V_B - V_A) \). On an equipotential surface the potential has the same value at every point, so the potential difference between any two points of the surface is zero.
\( W = q\,\Delta V = 1\,\mathrm{C}\times0 = 0 \)
The distance (20 cm) does not matter. Equivalently, the electric field is normal to the surface, so the force is perpendicular to the displacement along the surface and \( \vec{F}\cdot\vec{d} = 0 \).
NCERT (2026-27):
Equipotential Surfaces – “… But this is in contradiction to the definition of an equipotential surface: there is no potential difference between any two points on the surface and no work is required to move a test charge on the surface.”